Driving device intended for apparatus for recording and reproducing sound



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H. FIGDOR ETAL DRIVING DEVICE INTENDED FOR APPARATUS FOR Filed Oct. 22, 1958 RECORDING AND REPRODUCING SOUND May 30, 1961 nag BY 1 f,

g AGEN United States Patent P DRIVING DEVICE INTENDED FOR APPARATUS FOR RECORDING AND REPRODUCING SOUND Hans Figdor, Friedrich Kindl, Theodor Maiwald, Gerold Schager, and Ferdinand Zecha, all of Vienna, Austria, assignors to North American Philips Company, Inc New York, N.Y., a corporation of Delaware Filed Oct. 22, 1958, Ser. No. 768,893

Claims priority, application Austria Oct. 23, 1957 3 Claims. (Cl. 74-207) This invention relates to driving devices intended for apparatus for recording and reproducing sound, in which the rotation of the shaft of the motor is transmitted, by means of a friction wheel having a shaft movable parallel to itself, to a driving wheel driving the transportation member for the sound carrier directly.

In order to prevent in such apparatus any interferences brought about by variations in the speed of the sound carrier and known under the name wobbling, it is necessary and in each case also possible to avoid in the transportation member for the sound carrier (turn-table for sound carriers in the form of records, roller for sound carriers in the form of sheets, spool or coil for elongated sound carriers, etc.) any stroke and play of the shaft and also non-circularity of the surfaces to which the movement of the motor is transmitted or which transmit their movement to the sound carrier. However, the rotation of the driving motor always shows greater or smaller irregularities. Consequently, in constructing a driving device, the essential point frequently consists in avoiding such irregularities in the transmission of the movement of the motor to the transportation member for the sound carrier so that the transportation member is actually driven at constant speed.

It is known for this purpose to provide the transportation member for the sound carrier with a fly-wheel and/ or to bring about the transmission of the rotation of the motor to said transportation member by means of elastic ropes. Arranging fly-wheels renders the apparatus heavier and more expensive. Connecting the transportation member to the electric motor by means of a rope has the disadvantage that in such a device the transportation member for the sound carrier cannot be stopped without further expedients when the motor keeps rotating.

This is possible in a very simple manner in a known driving device in which an intermediate wheel which can be introduced at will brings about the desired driving coupling between the shaft of the motor and a wheel driving the transportation member directly. In such a device a very rigid coupling certainly exists between the shaft of the motor and the transportation member, with the result that irregularities in the rotation of the motor are completely transmitted to the transportaion member for the sound carrier. Such driving devices thus hitherto yielded satisfactory results only if the whole of the driv ing mechanism and more particularly the electric motor was built up with great accuracy and, where possible, the inertia moment of the transportation member for the sound carrier was great due to the presence of flywheel. In the case of small, light and inexpensive apparatus, in which such precautions are not justified, a comparatively poor quality of recording and reproduction had to be taken into the bargain. For such cases the present invention provides an improvement with simple means.

According to the invention, in a driving deviceintended for apparatus for recording and reproducing sound, in

Patented May 30, 1961 which the rotation of the shaft of the motor is transmitted by means of a friction wheel having a shaft journalled to be movable parallel to itself to a driving wheel driving the transportation member for the sound carrier directly, a support and also a spring for supporting the shaft of the friction wheel are provided on the side opposite the shaft of the motor approximately in the plane connecting the shaft of the friction wheel and the shaft of the motor, the spring keeping the shaft of the friction wheel itself, or its journal, continuously in engagement with the supporting surface of the support. In one special embodiment of the device according to the invention, the support comprises the journal of a pivotal lever carrying the shaft of the friction Wheel.

Irregularities in the structure of the driving motor have their effect in the form of irregular vibration of the motor shaft which is directly transmitted to the shaft of the friction wheel and hence directly to the driving wheel of the transportation member for the sound carrier. The components of this movement which extend tangentially to the circumference of the driving wheel are the principal source of the interferences in the regular running of the sound carrier since they act to the full extent upon the peripheral speed of the driving wheel even if the driving wheel is used for decreasing the speed. However, since due to the arrangement according to the invention the shaft of the friction wheel cannot slide in the plane extending from the shaft of the driving wheel to the shaft of the motor, it is not capable of transmitting variations in position in tangential direction to the circumference of the driving wheel. The device according to the invention makes it possible, for example, to drive a sound tape in a manner such that, without the smooth transport roller otherwise usually employed, only the winding coil of the sound carrier is driven Without the inertia moment of the winding device being increased by arranging an additional fly-wheel.

In order that the invention may be readily carried into effect, it will now be described in detail, by way of example, with reference to the accompanying drawing showing two embodiments of the driving device for an apparatus in which only the winding coil of the tape-like sound carrier is driven. For the sake of clarity, the drawing is partly diagrammatic and all those parts which are not essential to the invention are omitted.

In the embodiment shown in Fig. 1, a separate support 9 is provided for the idler shaft 8 of the friction idler wheel 5, in the embodiment shown in Fig. 2, the support is constituted by the journal of a pivotal lever 21 carrying the friction idler wheel 5.

The table 1 of the winding coil is journalled on the chassis of the apparatus and has the form of a driving wheel. The table 1 is provided at its circumference with a friction coating 2 which is preferably elastic. A friction idler wheel 5 can be introduced between the shaft 3 of the motor 4, which is of the driving shaft type, and the driving idler wheel 1, the friction idler wheel 5 having two stages 6 and 7 for reducing the speed, the firstmentioned of which also has a friction coating which is preferably elastic. The idler shaft 8 of friction idler wheel 5 is journalled in a lever 9. The lever 9 is pivoted on a shaft 10, which is journalled in a lever 11 which is pivoted on a shaft 12. The lever 11 carries an armature 13 of a relay 14. A spring 15 has a tendency to pull the armature 13 from the relay 14 and to bring the friction wheel 5 via the lever 9 out of its position of engagement. When the relay 14 keeps the armature 13 attracted, the friction idler wheel 5 is pressed against the shaft 3 and the table 1. In this position, the idler shaft 8 engages with a support 16 adjustably secured to the chassis by means of screws 17. It is supported by the supporting surface 16' on the opposite side of the shaft of the motor and in the plane extending between the shaft of the motor and the shaft of the friction wheel 5. The supporting surface 16 extends at this area at right angles to the plane between the shaft of the motor and the shaft of the friction wheel. A spring 18, which engages the idler shaft 8 on the side remote from its journal, keeps the idler shaft 8 in continuous engagement With the supporting surface 16. The rest position 19 occupied by the friction idler wheel when the relay 14 is not energized, is determined by a recess 20 in the supporting surface 16'. The support 16 is adjusted when the friction wheel 5 occupies the position of engagement.

With suitable construction of the journal of the idler shaft 8 of the friction idler wheel 5, it may be supported, instead of by the idler shaft 8 itself, either by the journal or by the support of this journal. In the arrangement shown in Fig. 2, the idler shaft 8 of the friction idler wheel 5 is journalled in a lever 21. The journal axis 22 of this lever lies in the plane between the shaft of the motor and the shaft of the friction wheel. The spindle of the journal 22 thus serves as a support for the idler shaft 8 of the friction idler wheel 5, which in turn is pressed against this support by the spring 18. Means, which are not shown, make it possible for the lever 21 to pivot in directions 23 and 24 and thus bring the friction idler wheel 5 out of the position of engagement or into the position of engagement.

As noted above, table 1 illustrated in the drawing may be a turntable for record players, a reel for tape recorder, or a roller, etc. In the claims, however, turntable is used in a generic sense to include turntables, reels, rollers and the like.

What is claimed is:

l. A turntable drive device comprising a motor provided with a drive shaft, an idler wheel having a. shaft for selectively drivingly engaging a turntable, means journalling said idler shaft whereby said shaft is movable to positions parallel to the longitudinal axis of said drive shaft, a support for said idler wheel shaft and a spring for supporting said idler wheel shaft being located on said device at the side of said idler wheel shaft opposite to said motor shaft, said spring being operatively connected to the shaft of said idler wheel whereby said idler wheel shaft is maintained in continuous engagement with said support.

2. A turntable drive device comprising a motor provided with a drive shaft, an idler wheel having a shaft for selectively drivingly engaging a turntable, means journalling said idler shaft whereby said shaft is movable to positions parallel to the longitudinal axis of said drive shaft, a support for said idler wheel shaft and a spring for supporting said idler wheel shaft being located on said device at the side of said idler Wheel shaft opposite said motor shaft approximately in a plane extending from said idler wheel shaft to said motor shaft, said spring being operatively connected to the shaft of said idler wheel, said support being an elongated arm, and said spring maintaining said idler wheel shaft in continuous engagement with the free end of said elongated arm.

3. A turntable drive device as claimed in claim 2 wherein said elongated arm is provided with a recess at the free end thereof whereby when said idler wheel shaft is located in said recess idler wheel is out of engagement with said turntable.

References Cited in the file of this patent UNITED STATES PATENTS in- I 

